Bk 521-406BG Malleable Black Iron Pipe Cap 1-1/4 in

Product Description

The BK 521-406BG is a 1-1/4 inch malleable black iron pipe cap used to close off the end of a threaded pipe run. Manufactured from black malleable iron conforming to ANSI/ASTM A-197, this cap meets dimensional standards ANSI/ASME B16.3, B16.14, and B16.39, with threads cut to ANSI B1.20.1. Each fitting is individually flag tagged and 100% inspected before leaving the facility. The Mueller logo is cast directly into the body of the fitting. Plumbers and pipefitters install this cap in gas, water, and general plumbing distribution systems where a threaded pipe end requires permanent or semi-permanent closure.

This cap is suited for residential and light commercial plumbing and gas piping applications. It fits standard 1-1/4 inch NPT threaded pipe ends and is commonly used during pressure testing to cap off branch lines, or as a permanent end closure on black iron gas piping. The black iron finish makes it appropriate for gas distribution systems where galvanized fittings are not permitted by code.

Key Features

• Black malleable iron construction per ANSI/ASTM A-197 for durability in gas and plumbing systems
• Threads conform to ANSI B1.20.1 for reliable NPT fit
• Dimensions meet ANSI/ASME B16.3, B16.14, and B16.39 standards
• Mueller logo cast into fitting body for manufacturer traceability
• Individually flag tagged and 100% inspected at the factory

Compatibility

Designed as an OEM-style replacement or new-installation fitting for standard 1-1/4 inch NPT threaded black iron pipe systems in gas and plumbing applications.

Installation Notes

Installation is performed by licensed plumbers or pipefitters in accordance with the International Fuel Gas Code (IFGC) or International Plumbing Code (IPC) as applicable. Shut off and depressurize the pipe system completely before installing or removing any threaded fittings. Apply an approved thread sealant or PTFE tape rated for the intended service medium before threading the cap onto the pipe. Do not over-tighten; use a pipe wrench and tighten to a snug, leak-free fit confirmed by pressure test.

Technical Specifications

• Material: Malleable Black Iron, ANSI/ASTM A-197
• Pipe Size: 1-1/4 inches
• Thread Standard: ANSI B1.20.1 (NPT)
• Dimensional Standards: ANSI/ASME B16.3, B16.14, B16.39
• Weight: 0.475 pounds
• Sold As: Each

Standard Information

• Brand: BK
• Manufacturer Part Number: 521-406BG